R&S ZNB Series User Manual

Concepts and features
R&S
®
ZNB/ZNBT
161User Manual 1173.9163.02 ─ 62
Multiple traces can be written to the same shared memory buffer. For each of these
traces, the firmware stores a configurable number of formatted or unformatted trace
values to a contiguous part of the shared memory.
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A formatted (real) trace value takes up 8 bytes of memory.
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An unformatted (complex) trace value takes up 16 bytes: 8 bytes for the real part, 8
bytes for the imaginary part.
Memory-mapped trace data transfer is a pure remote control feature. Once set up, the
VNA firmware refreshes the shared memory trace data with every sweep. Other pro-
cesses can read these data via standard APIs for Windows Named Shared Memory
that are available for various programming languages.
You can create multiple shared memory buffers, e.g. with different intended life span.
Set up a shared memory buffer
The setup of a shared memory buffer and the allocation of trace data is performed by a
sequence of SYSTem:DATA:MEMory... commands, starting with an INITialize and
finished by a COMMit.
1. Initialize the shared memory buffer:
SYSTem:DATA:MEMory:INITalize
2. Add traces:
a) SYSTem:DATA:MEMory:ADD '<TrName1>', FDATA|SDATa, #Values1
Select an existing trace name, choose whether to use formatted trace data
(FDATa) or unformatted trace data (SDATa), and define how many trace values
the firmware writes to the buffer per sweep.
The data block of the first trace has an offset of 0 bytes relative to the start of
the shared memory buffer.
b)
SYSTem:DATA:MEMory:ADD '<TrName2>', FDATA|SDATa, #Values2
Use SYSTem:DATA:MEMory:OFFSet? to query the offset in bytes of the sec-
ond trace data block. Processes that want to read the trace data from the buffer
need to know this offset. Its size depends on whether the first trace data block
contains formatted (real) or unformatted (complex) values.
c) ...
Use SYSTem:DATA:MEMory:OFFSet? to query the offset of the last added trace.
3. Create the named shared memory buffer:
SYSTem:DATA:MEMory:COMMit '<ShMemName>'
The name must be unique. Before the COMMit you can use SYSTem:DATA:
MEMory:CATalog? to query the names of existing shared memory buffers.
The size of the last created shared memory buffer can be queried using SYSTem:
DATA:MEMory:SIZE?.
Operations on traces

R&S ZNB Series Specifications

General

Brand	R&S
Model	ZNB Series
Category	Measuring Instruments
Language	English